[PATCH v4 02/15] ARM: ARMv7-M: Enlarge vector table up to 256 entries

>From Cortex-M reference manuals, the nvic supports up to 240 interrupts. So the number of entries in vectors table is up to 256. This patch adds a new config flag to specify the number of external interrupts. Some ifdeferies are added in order to respect the natural alignment without wasting too

[PATCH v4 02/15] ARM: ARMv7-M: Enlarge vector table up to 256 entries

From Cortex-M reference manuals, the nvic supports up to 240 interrupts. So the number of entries in vectors table is up to 256. This patch adds a new config flag to specify the number of external interrupts. Some ifdeferies are added in order to respect the natural alignment without wasting too